How much will a coin be decreased in value due to a defect. In my case, I have a 1860-S 50 cent piece graded by ANACS as "cleaned", but AU-50 details. This coin is one of my "better" coins and for insurance purposes want to give it a somewhat correct value. It's not heavily cleaned (whizzed or otherwise defaced). I'm trying to learn how to post pics on this site, so for now a description is all I've got.
30-50% off the problem free And it depends on how harshly cleaned and eye appeal of the result Not an exact science
USA Coin Book lists it for $600 in AU. Since it has been cleaned, it could be $300. However, it is a key date and if it has good eye appeal despite the cleaning, someone may need it as a hole filler and could pay $400-$500. It's hard to say without seeing clear photos of both sides in order to determine the degree of cleaning. If it was lightly cleaned, that will retone over time, and if it was harshly cleaned then you are $300 or less.